Fifteen pro-regime military officials -- including four Russian generals -- have been killed by opposition forces in northwestern Syria near the border with Turkey, Syrian opposition sources said Wednesday.

According to the sources, who spoke on condition of anonymity, the slain military officials included four Russian generals and four Syrian generals who had met late Tuesday in Turkmen Mountain -- located in Syria’s northern Latakia region -- to discuss recent military developments.

One of the slain Russian generals, identified only as "Yuri", was reportedly coordinating regime attacks in Turkmen Mountain, the sources added.

In a statement issued later in the day, the Russian Defense Ministry confirmed death of one Russian officer in Syria but did not mention his name or rank.

The statement said the officer was in Syria for "military consultancy on use of weapons" and was killed on Feb. 1 during an attack on a military post that belongs to the Syrian regime.

The statement blamed the attack on Daesh.

Predominantly Turkmen areas of northwestern Syria have been under attack by regime forces -- backed by Russian air power -- since November of last year.

Recent attacks in these areas have displaced thousands of Turkmen, a Turkic ethnic group concentrated mainly in Syria and Iraq, prompting many to seek refuge in southern Turkey.